Even 1 Bitcoin is enough to change the life of somebody from a poorer country. It can be a large house in many countries.
I suppose while it is a giant prize, it is not going to be as attractive to so many players. I mean. A million sounds even better, but I would rather throw my money at a big win with better chances than basically play lottery.
As for me the prize of 1 BTC will always be attractive for a large part of the audience especially if such a prize can drop from the wheel on the Betfury site or any other gambling platform because after a few years the rate of 1 BTC can grow up to $250k and up to $500k and even up to $1 million. The only thing is that not every gambler will have the patience to hold BTC for so long, especially for those who got it easily.